Magnetic recording medium

Abstract

A magnetic recording medium includes: a non-magnetic support; and a magnetic layer including a binding agent and a ferromagnetic powder including at least one epsilon-type iron oxide compound selected from the group consisting of ε-Fe 2 O 3 and compound represented by Formula (1) (A represents at least one metal element other than Fe, and a satisfies 0<a<2), in which a value of magnetic field Hc with respect to magnetic field Hc′ is from 0.6 to 1.0, and Hc′ satisfies Expression (II): 119 kA/m<Hc′<2380 kA/m. The magnetic field Hc′ is a magnetic field when the value of Expression (I): d 2 M/dH 2 is zero, wherein a magnetization M, which is obtained by a magnetic field-magnetization curve obtained by measurement under specific conditions, is subjected to second derivative with respect to an applied magnetic field H, and magnetic field Hc is a magnetic field when the magnetization is zero in the curve. ε-A a Fe 2-a O 3   (1)

What is claimed is: 
     
         1 . A magnetic recording medium, comprising:
 a non-magnetic support; and   a magnetic layer that is provided on the non-magnetic support and that comprises a ferromagnetic powder and a binding agent, the ferromagnetic powder comprising at least one epsilon-type iron oxide compound selected from the group consisting of ε-Fe 2 O 3  and a compound represented by the following Formula (1),   wherein a value of a magnetic field Hc with respect to a magnetic field Hc′ is from 0.6 to 1.0, and Hc′ satisfies the following Expression (II),   wherein the magnetic field Hc′ is a magnetic field when the value of the following Expression (I) is zero, wherein a magnetization M, which is obtained by a magnetic field-magnetization curve obtained by measurement at a maximum applied magnetic field of 359 kA/m, a temperature of 296 K, and a magnetic field sweeping speed of 1.994 kA/m/s, is subjected to a second derivative with respect to an applied magnetic field H, and wherein the magnetic field Hc is a magnetic field when the magnetization is zero in the magnetic field-magnetization curve:
     d   2   M/dH   2   Expression (I)
 
   119 kA/m< Hc ′<2380 kA/m  Expression (II)
 
   ε-A a Fe 2-a O 3   (1)
 
   wherein, in Formula (1), A represents at least one metal element other than Fe, and a satisfies a relationship of 0<a<2.   
     
     
         2 . The magnetic recording medium according to  claim 1 , wherein the binding agent comprises a binding agent having a crosslinked structure. 
     
     
         3 . The magnetic recording medium according to  claim 1 , wherein a value of Hc with respect to Hc′ is from 0.65 to 1.0. 
     
     
         4 . The magnetic recording medium according to  claim 1 , wherein a value of Hc with respect to Hc′ is from 0.71 to 1.0. 
     
     
         5 . The magnetic recording medium according to  claim 1 , wherein a content of the binding agent is 5 parts by mass to 30 parts by mass with respect to 100 parts by mass of the ferromagnetic powder. 
     
     
         6 . The magnetic recording medium according to  claim 1 , wherein a mass ratio of mass of a nonvolatile component with respect to mass of the ferromagnetic powder in the magnetic layer is from 0.15 to 1.8. 
     
     
         7 . The magnetic recording medium according to  claim 1 , wherein a thickness of the magnetic layer is 10 nm to 350 nm. 
     
     
         8 . The magnetic recording medium according to  claim 1 , wherein A in Formula (1) is at least one metal element selected from the group consisting of Ga, Al, In, Nb, Co, Zn, Ni, Mn, Ti, and Sn. 
     
     
         9 . The magnetic recording medium according to  claim 8 , wherein the compound represented by Formula (1) comprises Ga, and an atomic composition percentage of Ga atoms is 5 atom % to 50 atom % with respect to Fe atoms.